FDC37C78 View Datasheet(PDF) - SMSC -> Microchip

Part Name

Description

Manufacturer

FDC37C78

Floppy Disk Controller

SMSC -> Microchip 

PIN NO.

NAME

38 Reset

21 Read Disk Data

27 Write

Data

29 Head

Select

DESCRIPTION OF PIN FUNCTIONS

BUFFER

SYMBOL TYPE

DESCRIPTION

RESET

IS This active high signal resets the chip and

must be valid for 500 ns minimum. The effect

on the internal registers is described in the

appropriate section. The configuration

registers are not affected by this reset.

FLOPPY DISK INTERFACE

nRDATA

nWDATA

nHDSEL

IS

OD20

OD20

Raw serial bit stream from the disk drive, low

active. Each falling edge represents a flux

transition of the encoded data.

This active low high current driver provides

the encoded data to the disk drive. Each

falling edge causes a flux transition on the

media.

This high current output selects the floppy

disk side for reading or writing. A logic "1" on

this pin means side 0 will be accessed, while

a logic "0" means side 1 will be accessed.

33 Direction

Control

31 Step Pulse

nDIR

nSTEP

20 Disk Change

nDSKCHG

22, DRVDEN 0,

23 DRVDEN 1

24 Density Select

DRVDEN0,

DRVDEN1

DENSEL

OD20

OD20

IS

OD20

OD20

This high current low active output determines

the direction of the head movement. A logic

"1" on this pin means outward motion, while a

logic "0" means inward motion.

This active low high current driver issues a

low pulse for each track-to-track movement of

the head.

This input senses that the drive door is open

or that the diskette has possibly been

changed since the last drive selection. This

input is inverted and read via bit 7 of I/O

address 3F7H.

Indicates the drive and media selected. Refer

to configuration registers CR03, CR0B,

CR1F.

Indicates whether a low (250/300 Kb/s) or

high (500 Kb/s) data rate has been selected.

This is determined by the IDENT bit in

Configuration Register 3.

7

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